The present invention relates to the preparation of a branched polyolefins, the intermediate products and the processes to obtain these products.
Commercially available polyethylene and polypropylene prepared using standard procedures with Ziegler-Natta or metallocene catalysts have a predominantly linear molecular structure. Although linear polyolefins have many desirable physical properties, they show a variety of melt processing shortcomings, especially the metallocene prepared ones having narrow molecular weight distributions, which typically have a low melt strength. Low melt strength is a problem because it causes local thinning in melt thermoforming, relative weakness in large-part blow molding and flow instabilities in co-extrusion of laminates.
One way of overcoming the shortcomings of linear polyolefins is by means of branching, viz. the provision of polymer side chains extending from the polyolefin backbone.
In the prior art different approaches have been developed to prepare branched polyolefins including methods based on chain transfer concepts.
Despite their ubiquitous presence in our society, polyolefins such as polyethylene and polypropylene are not appropriate for several applications as a consequence of their inherently nonpolar character. This nonpolar character is the reason for the poor adhesion, printability and compatibility that can restrict their efficacy. Hence, it is further desirable to prepare branched polyolefins having end functionalized branches with for example polar end groups so that the branched polyolefins also exhibit good adhesion and printability.
This invention is directed towards an improved process for the preparation of branched polyolefins and branched polyolefins having end functionalized branches.
One or more of these aims are obtained by the process according to the present invention.                It is an aim of the present invention to provide a process for the preparation of main group metal, preferably aluminum-functionalized hydrocarbyl chain growth products.        It is an aim of the present invention to provide a process for the preparation of branched polyolefins.        It is an aim of the present invention to provide a process for the preparation of branched polyolefins having end-functionalized branches.        It is moreover an aim of the present invention to provide branched polyolefins.        It is moreover an aim of the present invention to provide branched polyolefins having end-functionalized branches.        One or more of these aims are obtained by the catalyst system according to the present invention.        